1. Field of the Invention
This invention generally relates to display devices for emitting light of several different colors and more specifically to a display device having several stable states characterized by respectively different colors.
2. Description of the Prior Art
A multicolor semiconductor lamp comprising a plurality of light emitting diodes for emitting light of respectively different colors is disclosed in U.S. Pat. No. 3,875,456 issued on Apr. 1, 1975 to Tsuyoshi Kano et al. The light emitting diodes are closely adjacent and covered by a layer of light scattering material to provide an appearance of a single light source.
A circuit for selectively illuminating one of a pair of parallel back-to-back coupled light emitting diodes is disclosed in U.S. Pat. No. 4,484,105 issued on Nov. 20, 1984 to Richard J. Kriete et al. Two photon-emitting devices and two photon-responsive devices are additionally provided for selectively reversing current flow through the back-to-back coupled light emitting diodes to illuminate them either in red or green color. Since the two light emitting diodes are coupled to conduct current in opposite directions, they cannot be illuminated simultaneously to blend their emissions.
A display device capable of exhibiting more than two stable states characterized by respectively different colors is unknown.